.picture {
    width: 100%;
    height: 520px;
    background-image: url("../image/jju_5.jpg");
}
.centerbox {
    margin: 0 auto;
    width: 1300px;
    height: 520px;
    display: inline-block;
}
.centerbox img {
    width: 100%;
    height: 100%;
}
#forword {
    width: 86px;
    height: 100%;
    float: left;
    background-color:rgba(0, 0, 0, .5);
}
#back {
    background-color: rgba(0, 0, 0, .5);
    width: 86.5px;
    height: 100%;
    float: right;
}
#forwordleft {
    position: relative;
    top: 320px;
    margin: 0 auto;
    width: 32px;
    height: 45px;
    background: url("../image/slider-arrow.png") no-repeat -192px -142px;
}
#backright {
    position: relative;
    top: 320px;
    margin: 0 auto;
    width: 32px;
    height: 45px;
    background: url("../image/slider-arrow.png") no-repeat -80px -142px;
}
#forword:hover #forwordleft {
    background-position:-134px -142px ;
}
#back:hover #backright {
    background-position:-16px -142px ;
}